Dyslexic readers and saccade computation: effects of reading exposure and visuo-perceptual constraints
Résumé
Some findings suggest the presence of preferred landing position (PLP) effects in children who are learning to read. Recently it has been shown that, in children from first to fifth grade, stimulus location has a strong effect on oculomotor development and lexical-decision time, in both central and parafoveal vision (Ducrot et al., 2013). The establishment of the PLP, which seems to be due to an eye-guiding mechanism based on a perceptual low-level processing, could also be influenced by print exposure. How does saccadic programming develop in children with reading impairment? We assessed the eye movements of three groups of children: dyslexic readers, unimpaired reading-level controls, and unimpaired chronological-age controls, using a lateralized bisection task (participants were asked to move their eyes to a position they thought to be the middle of the stimulus, Ducrot & Pynte, 2002). The type of stimulus - linguistic factor (words vs non-linguistic stimuli) and discreteness (lines vs strings of hashes) - in combination with the stimulus presentation side (left vs. right) were manipulated. If reading exposure influences saccadic programming we should expect different PLP pattern for normal readers and for dyslexics. Results are discussed with respect to current theories of developmental dyslexia.